I use rlcompleter extensively in interactive Python
mode.
I think it could be cool if callable objects were added
"("
when completed. This way it will be much faster to 
program, without looking-up __doc__. For example:

>>> f.fil<TAB>
will give:
>>> f.fileno(_
("_" is to mark cursor position)
and:

>>> f.so<TAB>
will (as before) give:
>>> f.softspace _